This plugin simplifies the process of adding responsive css and creating breakpoints. It reduces code redundancy of declaring breakpoints. Also, it provides field to add css regardless of resposiveness under the custom css metabox. After installation, five breakpoints are created by default. You can delete those breakpoints or add new breakpoints and also order them as desired.
Plugin Documentation:
http://www.wpwox.com/responsive-css-editor/
- There are two ways to install the plugin:
a) Use the 'automatic install from the Wordpress plugin directory' option in the
Wordpress admin panel. Search for "Responsive CSS Editor"
OR
b) Download the zip-file, and use the 'upload' option in the Wordpress > admin panel > plugins > new plugin > upload plugin
- Activate the plugin through the 'Plugins' menu in WordPress
Modify the plugin settings in Responsive CSS Settings after installation.